[cpu-detection] Cleanup of Host.cpp.

[asbirlea]

Summary

Mirroring most cleanup changed from compiler-rt/lib/builtins/cpu_model.
x86 methods are still returning a bool.

[echristo]

LGTM.

Thanks.

-eric

lib/Support/Host.cpp

 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/ADT/Triple.h"
 #include "llvm/Config/config.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/raw_ostream.h"
 #include <string.h>
+#include <assert.h>
+#include <cpuid.h>
 
 // Include the platform-specific parts of this class.
 #ifdef LLVM_ON_UNIX
 #include "Unix/Host.inc"
 #endif
 #ifdef LLVM_ON_WIN32
 #include "Windows/Host.inc"
 #endif
static ssize_t LLVM_ATTRIBUTE_UNUSED readCpuInfo(void *Buf, size_t Size) {
   int Ret = read(FD, Buf, Size);
   int CloseStatus = close(FD);
   if (CloseStatus)
     return -1;
   return Ret;
 }
 #endif
 
-#if defined(i386) || defined(__i386__) || defined(__x86__) ||                  \
-    defined(_M_IX86) || defined(__x86_64__) || defined(_M_AMD64) ||            \
-    defined(_M_X64)
+#if defined(__i386__) || defined(_M_IX86) || \
+    defined(__x86_64__) || defined(_M_X64)
 
 enum VendorSignatures {
   SIG_INTEL = 0x756e6547 /* Genu */,
   SIG_AMD = 0x68747541 /* Auth */
 };
 
 enum ProcessorVendors {
   VENDOR_INTEL = 1,
enum ProcessorFeatures {
   FEATURE_ADX,
   FEATURE_EM64T
 };
 
 /// getX86CpuIDAndInfo - Execute the specified cpuid and return the 4 values in
 /// the specified arguments.  If we can't run cpuid on the host, return true.
 static bool getX86CpuIDAndInfo(unsigned value, unsigned *rEAX, unsigned *rEBX,
                                unsigned *rECX, unsigned *rEDX) {
+#if defined(__GNUC__) || defined(__clang__) || defined(_MSC_VER)
 #if defined(__GNUC__) || defined(__clang__)
-#if defined(__x86_64__) || defined(_M_AMD64) || defined(_M_X64)
-  // gcc doesn't know cpuid would clobber ebx/rbx. Preseve it manually.
-  asm("movq\t%%rbx, %%rsi\n\t"
+#if defined(__x86_64__)
+  // gcc doesn't know cpuid would clobber ebx/rbx. Preserve it manually.
+  // FIXME: should we save this for Clang?
+  __asm__("movq\t%%rbx, %%rsi\n\t"
           "cpuid\n\t"
           "xchgq\t%%rbx, %%rsi\n\t"
           : "=a"(*rEAX), "=S"(*rEBX), "=c"(*rECX), "=d"(*rEDX)
           : "a"(value));
-  return false;
-#elif defined(i386) || defined(__i386__) || defined(__x86__) || defined(_M_IX86)
-  asm("movl\t%%ebx, %%esi\n\t"
+#elif defined(__i386__)
+  __asm__("movl\t%%ebx, %%esi\n\t"
           "cpuid\n\t"
           "xchgl\t%%ebx, %%esi\n\t"
           : "=a"(*rEAX), "=S"(*rEBX), "=c"(*rECX), "=d"(*rEDX)
           : "a"(value));
-  return false;
-// pedantic #else returns to appease -Wunreachable-code (so we don't generate
-// postprocessed code that looks like "return true; return false;")
 #else
-  return true;
+  assert(0 && "This method is defined only for x86.");
 #endif
 #elif defined(_MSC_VER)
   // The MSVC intrinsic is portable across x86 and x64.
   int registers[4];
   __cpuid(registers, value);
   *rEAX = registers[0];
   *rEBX = registers[1];
   *rECX = registers[2];
   *rEDX = registers[3];
+#endif
   return false;
 #else
   return true;
 #endif
 }
 
 /// getX86CpuIDAndInfoEx - Execute the specified cpuid with subleaf and return
 /// the 4 values in the specified arguments.  If we can't run cpuid on the host,
 /// return true.
 static bool getX86CpuIDAndInfoEx(unsigned value, unsigned subleaf,
                                  unsigned *rEAX, unsigned *rEBX, unsigned *rECX,
                                  unsigned *rEDX) {
-#if defined(__x86_64__) || defined(_M_AMD64) || defined(_M_X64)
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__) || defined(_MSC_VER)
+#if defined(__x86_64__) || defined(_M_X64)
+#if defined(__GNUC__) || defined(__clang__)
   // gcc doesn't know cpuid would clobber ebx/rbx. Preseve it manually.
-  asm("movq\t%%rbx, %%rsi\n\t"
+  // FIXME: should we save this for Clang?
+  __asm__("movq\t%%rbx, %%rsi\n\t"
           "cpuid\n\t"
           "xchgq\t%%rbx, %%rsi\n\t"
           : "=a"(*rEAX), "=S"(*rEBX), "=c"(*rECX), "=d"(*rEDX)
           : "a"(value), "c"(subleaf));
-  return false;
 #elif defined(_MSC_VER)
   int registers[4];
   __cpuidex(registers, value, subleaf);
   *rEAX = registers[0];
   *rEBX = registers[1];
   *rECX = registers[2];
   *rEDX = registers[3];
-  return false;
-#else
-  return true;
 #endif
-#elif defined(i386) || defined(__i386__) || defined(__x86__) || defined(_M_IX86)
-#if defined(__GNUC__)
-  asm("movl\t%%ebx, %%esi\n\t"
+#elif defined(__i386__) || defined(_M_IX86)
+#if defined(__GNUC__) || defined(__clang__)
+  __asm__("movl\t%%ebx, %%esi\n\t"
           "cpuid\n\t"
           "xchgl\t%%ebx, %%esi\n\t"
           : "=a"(*rEAX), "=S"(*rEBX), "=c"(*rECX), "=d"(*rEDX)
           : "a"(value), "c"(subleaf));
-  return false;
 #elif defined(_MSC_VER)
   __asm {
       mov   eax,value
       mov   ecx,subleaf
       cpuid
       mov   esi,rEAX
       mov   dword ptr [esi],eax
       mov   esi,rEBX
       mov   dword ptr [esi],ebx
       mov   esi,rECX
       mov   dword ptr [esi],ecx
       mov   esi,rEDX
       mov   dword ptr [esi],edx
   }
-  return false;
+#endif
 #else
-  return true;
+  assert(0 && "This method is defined only for x86.");
 #endif
+  return false;
 #else
   return true;
 #endif
 }
 
 static bool getX86XCR0(unsigned *rEAX, unsigned *rEDX) {
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
   // Check xgetbv; this uses a .byte sequence instead of the instruction
   // directly because older assemblers do not include support for xgetbv and
   // there is no easy way to conditionally compile based on the assembler used.
   __asm__(".byte 0x0f, 0x01, 0xd0" : "=a"(*rEAX), "=d"(*rEDX) : "c"(0));
   return false;
 #elif defined(_MSC_FULL_VER) && defined(_XCR_XFEATURE_ENABLED_MASK)
   unsigned long long Result = _xgetbv(_XCR_XFEATURE_ENABLED_MASK);
   *rEAX = Result;
static unsigned getAvailableFeatures(unsigned int ECX, unsigned int EDX,
   Features |= (((EDX >> 29) & 0x1) << FEATURE_EM64T);
   return Features;
 }
 
 StringRef sys::getHostCPUName() {
   unsigned EAX = 0, EBX = 0, ECX = 0, EDX = 0;
   unsigned MaxLeaf, Vendor;
 
+  //FIXME: include cpuid.h from clang or copy __get_cpuid_max here
+  // and simplify it to not invoke __cpuid (like cpu_model.c in
+  // compiler-rt/lib/builtins/cpu_model.c?
+  if(!__get_cpuid_max(0, &Vendor))
+    return "generic";
   if (getX86CpuIDAndInfo(0, &MaxLeaf, &Vendor, &ECX, &EDX))
     return "generic";
   if (getX86CpuIDAndInfo(0x1, &EAX, &EBX, &ECX, &EDX))
     return "generic";
 
   unsigned Brand_id = EBX & 0xff;
   unsigned Family = 0, Model = 0;
   unsigned Features = 0;
StringRef sys::getHostCPUName() {
   }
 
   return "generic";
 }
 #else
 StringRef sys::getHostCPUName() { return "generic"; }
 #endif
 
-#if defined(i386) || defined(__i386__) || defined(__x86__) ||                  \
-    defined(_M_IX86) || defined(__x86_64__) || defined(_M_AMD64) ||            \
-    defined(_M_X64)
+#if defined(__i386__) || defined(_M_IX86) || \
+    defined(__x86_64__) || defined(_M_X64)
 bool sys::getHostCPUFeatures(StringMap<bool> &Features) {
   unsigned EAX = 0, EBX = 0, ECX = 0, EDX = 0;
   unsigned MaxLevel;
   union {
     unsigned u[3];
     char c[12];
   } text;